1/* Round to nearest integer value, rounding halfway cases to even.
2 flt-32 version.
3 Copyright (C) 2016-2023 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#define NO_MATH_REDIRECT
21#include <math.h>
22#include <math_private.h>
23#include <libm-alias-float.h>
24#include <math-use-builtins.h>
25#include <stdint.h>
26
27#define BIAS 0x7f
28#define MANT_DIG 24
29#define MAX_EXP (2 * BIAS + 1)
30
31float
32__roundevenf (float x)
33{
34#if USE_ROUNDEVENF_BUILTIN
35 return __builtin_roundevenf (x);
36#else
37 uint32_t ix, ux;
38 GET_FLOAT_WORD (ix, x);
39 ux = ix & 0x7fffffff;
40 int exponent = ux >> (MANT_DIG - 1);
41 if (exponent >= BIAS + MANT_DIG - 1)
42 {
43 /* Integer, infinity or NaN. */
44 if (exponent == MAX_EXP)
45 /* Infinity or NaN; quiet signaling NaNs. */
46 return x + x;
47 else
48 return x;
49 }
50 else if (exponent >= BIAS)
51 {
52 /* At least 1; not necessarily an integer. Locate the bits with
53 exponents 0 and -1 (when the unbiased exponent is 0, the bit
54 with exponent 0 is implicit, but as the bias is odd it is OK
55 to take it from the low bit of the exponent). */
56 int int_pos = (BIAS + MANT_DIG - 1) - exponent;
57 int half_pos = int_pos - 1;
58 uint32_t half_bit = 1U << half_pos;
59 uint32_t int_bit = 1U << int_pos;
60 if ((ix & (int_bit | (half_bit - 1))) != 0)
61 /* Carry into the exponent works correctly. No need to test
62 whether HALF_BIT is set. */
63 ix += half_bit;
64 ix &= ~(int_bit - 1);
65 }
66 else if (exponent == BIAS - 1 && ux > 0x3f000000)
67 /* Interval (0.5, 1). */
68 ix = (ix & 0x80000000) | 0x3f800000;
69 else
70 /* Rounds to 0. */
71 ix &= 0x80000000;
72 SET_FLOAT_WORD (x, ix);
73 return x;
74#endif /* ! USE_ROUNDEVENF_BUILTIN */
75}
76#ifndef __roundevenf
77libm_alias_float (__roundeven, roundeven)
78#endif
79